Problem $1$: Exercise $8\mathrm{.}18($with one change as mentioned below$)$

Instead of having a return type of void, your zip should return an integer: $0$ if execution is successful and $-1$ for malformed$/$error input. What would constitute a malformed input for this problem? For starters, it is an error to call zip with a nonempty list as third argument. It is also an error to call zip with one of the input lists the same as the output list. $($For instance, zip$($ll$1,$ll$2,$ll$1).$ Can you see the problem such a call would cause?$).$ On the other hand, it's OK to call zip with empty ll$1$ or ll$2($or both$).$ Finally, passing NULL pointers for some or all of the lists in not allowed either $($but you already knew that from previous assignments$).$ Your zip function should check all of these error conditions and return $-1$ if any of them are true.

Problem $2$: Exercise $8\mathrm{.}19($with one change just like in the above problem: return $0$ if execution is successful and $-1$ for malformed input$).$

What would constitute a malformed input for this problem? Use similar ideas as mentioned above in Problem $1.$ this is llist.c #include

#include

#include "llist.h$"$

$/*$ Private node ADT. $*/$

typedef struct $\_$node node;

struct $\_$node $\{$

node $*$ next;

void $*$ e;

$\}$;

static node $*$ newNode$($void $*$ e$)\{$

node $*$ n $=$ malloc$($sizeof$($node$))$;

if $(!$n$)$ return NULL;

n$->$next $=$ NULL;

n$->$e $=$ e;

return n;

$\}$

static void deleteNode$($node $*$ n$)\{$

free$($n$)$;

$\}$

$/*$ Linked list library. $*/$

struct $\_$llist $\{$

node $*$ head;

$\}$;

llist $*$ newLList$($void$)\{$

llist $*$ ll $=$ malloc$($sizeof$($llist$))$;

if $(!$ll$)$ return NULL;

ll$->$head $=$ NULL;

return ll;

$\}$

void deleteLList$($llist $*$ ll$)\{$

if $(!$ll$)$ return;

node $*$ n $=$ ll$->$head;

while $($n$)\{$

node $*$ next $=$ n$->$next;

deleteNode$($n$)$;

n $=$ next;

$\}$

free$($ll$)$;

$\}$

int isEmptyLList$($llist const $*$ ll$)\{$

if $(!$ll$)$ return $0$;

return$($ll$->$head $==$ NULL$)$;

$\}$

int putLList$($llist $*$ ll$,$ void $*$ e$)\{$

node $*$ n;

if $(!$ll$)$ return $-1$;

n $=$ newNode$($e$)$;

if $(!$n$)$ return $-1$;

n$->$next $=$ ll$->$head;

ll$->$head $=$ n;

return $0$;

$\}$

int getLList$($llist $*$ ll$,$ void $**$ e$)\{$

node $*$ n;

if $(!$ll $||!$e$)$ return $-1$;

if $($ll$->$head $==$ NULL$)\{/*$ nothing to get $*/$

$*$e $=$ NULL;

return $-2$;

$\}$

n $=$ ll$->$head;

$*$e $=$ n$->$e; $/*$ write element $*/$

ll$->$head $=$ n$->$next;

deleteNode$($n$)$;

return $0$;

$\}$

int peekLList$($llist const $*$ ll$,$ void $**$ e$)\{$

if $(!$ll $||!$e$)$ return $-1$;

if $($ll$->$head $==$ NULL$)\{$

$/*$ Nothing to get. $*/$

$*$e $=$ NULL;

return $-2$;

$\}$

$*$e $=$ ll$->$head$->$e; $/*$ write element $*/$

return $0$;

$\}$

int printLList$($llist const $*$ ll$,$ printFn f$)\{$

node $*$ n;

int cnt;

if $(!$ll $||!$f$)$ return $-1$;

cnt $=0$;

for $($n $=$ ll$->$head; n $!=$ NULL; n $=$ n$->$next$)\{$

$/*$ Print the index of the element. $*/$

cnt$++$;

printf$("\%$d:$",$ cnt$)$;

$/*$ Call user$-$provided f to print the element. $*/$

f$($n$->$e$)$;

$\}$

printf$("$

$")$;

return $0$;

$\}$

int zip$($llist $*$ ll$1,$ llist $*$ ll$2,$ llist $*$ ll$3)\{$

$/*$ Your code goes here. $*/$

return $0$;

$\}$

int unzip$($llist $*$ ll$1,$ llist $*$ ll$2,$ llist $*$ ll$3)\{$

$/*$ Your code goes here. $*/$

return $0$;

$\}$